Producing a desired compound using a biocatalyst has benefits such as mild reaction conditions, a higher purity level of the reaction product with fewer byproducts contained therein, and simplified production procedures. Accordingly, such a method is used for producing various compounds. To produce amide compounds, biocatalysts have been widely used since the discovery of nitrile hydratase, which is an enzyme to convert a nitrile compound to a corresponding amide compound.
As for industrially producing acrylamide using a biocatalyst, a so-called continuous reaction method is widely known; namely, while raw materials and a biocatalyst are introduced into a reaction vessel continuously or intermittently, a solution of the produced acrylamide is continuously or intermittently retrieved from the vessel. Examples of continuous reactions are described in patent publications 1˜4.
In a known method for continuously producing acrylamide, water is introduced into a reaction vessel in advance of initiating continuous reactions. Patent publications 1 and 2 describe methods for introducing water into a reaction vessel in advance of initiating continuous reactions. Also, in patent publications 3 and 4, after water and a biocatalyst are introduced in advance of initiating continuous reactions and are then heated to a predetermined temperature, acrylonitrile is supplied into the reaction vessel to initiate continuous reactions.